40
M. Maity et al.
1 Introduction
β-galactosidase has important application in food and medical industries due to their
ability of both hydrolytic and transglycosylation activities (Qi et al. 2017). This
enzyme can be used in milk and milk derivatives to decrease their lactose content and
thus solving the problem of low lactose solubility and its low degree of sweetening
(Kumar et al. 2015). Inadequate production of β-galactosidase leads to discomforts
such as cramps, gas, in digestion, diarrhea. β-galactosidase enhances the color, aroma,
and flavor of milk products. The creaminess of the ice cream increases due to lactose
hydrolysis (Erich et al. 2015). Regular milk and lactose-free milk have differences
in viscosity and whiteness. The lactose contents of milk and milk products are a
matter of concern for lactose-intolerant people. Technologies have to be applied
for the production of lactose-free milk and milk products from the regular milk.
β-galactosidase can commercially be applied in dairy industry to produce products
of low lactose content (Bosso et al. 2016). Factors such as pH, temperature, time,
lactose concentration, and presence of some activators alter the enzymatic hydrolysis
process (Triose et al. 2016). The present work was aimed at lactose hydrolysis of
milk by β-galactosidase obtained from soil bacteria and production of lactose-free
cheese.
2 Materials and Methods
2.1 Chemicals
Cow milk and starter culture tablet (Lactobascil plus ) were purchased from local
market, Shibpur, Howrah, India. Chemicals used in this study were of analytical
grade and purchased from Merck, Germany and Sigma-Aldrich, USA. Bacteriological media were procured from HiMedia laboratory Pvt. Ltd., India. The test kit of
oxidase–peroxidase for glucose estimation was purchased from Robonik (Prietest).
2.2 Screening and Isolation of β-Galactosidase-Producing
Microorganism
The β-galactosidase-producing bacteria were screened, isolated, and purified from
soil samples collected from cattle shed area. Soil samples were serially diluted
and plated on prestrerilized petriplates containing lactose media. Lactose medium
was containing per liter lactose 5 g, peptone 5 g, beef extract 3 g, agar 15 g,
and pH at 6.5 along with chromogenic substance 5-bromo-4-chloro-3-idolyl-β-dgalactopyranoside (X-gal) and incubated at 37 °C for 24 h. Strain was characterized
and identified using biochemical and morphological studies and verified by MTCC
M. Maity et al.
1 Introduction
β-galactosidase has important application in food and medical industries due to their
ability of both hydrolytic and transglycosylation activities (Qi et al. 2017). This
enzyme can be used in milk and milk derivatives to decrease their lactose content and
thus solving the problem of low lactose solubility and its low degree of sweetening
(Kumar et al. 2015). Inadequate production of β-galactosidase leads to discomforts
such as cramps, gas, in digestion, diarrhea. β-galactosidase enhances the color, aroma,
and flavor of milk products. The creaminess of the ice cream increases due to lactose
hydrolysis (Erich et al. 2015). Regular milk and lactose-free milk have differences
in viscosity and whiteness. The lactose contents of milk and milk products are a
matter of concern for lactose-intolerant people. Technologies have to be applied
for the production of lactose-free milk and milk products from the regular milk.
β-galactosidase can commercially be applied in dairy industry to produce products
of low lactose content (Bosso et al. 2016). Factors such as pH, temperature, time,
lactose concentration, and presence of some activators alter the enzymatic hydrolysis
process (Triose et al. 2016). The present work was aimed at lactose hydrolysis of
milk by β-galactosidase obtained from soil bacteria and production of lactose-free
cheese.
2 Materials and Methods
2.1 Chemicals
Cow milk and starter culture tablet (Lactobascil plus ) were purchased from local
market, Shibpur, Howrah, India. Chemicals used in this study were of analytical
grade and purchased from Merck, Germany and Sigma-Aldrich, USA. Bacteriological media were procured from HiMedia laboratory Pvt. Ltd., India. The test kit of
oxidase–peroxidase for glucose estimation was purchased from Robonik (Prietest).
2.2 Screening and Isolation of β-Galactosidase-Producing
Microorganism
The β-galactosidase-producing bacteria were screened, isolated, and purified from
soil samples collected from cattle shed area. Soil samples were serially diluted
and plated on prestrerilized petriplates containing lactose media. Lactose medium
was containing per liter lactose 5 g, peptone 5 g, beef extract 3 g, agar 15 g,
and pH at 6.5 along with chromogenic substance 5-bromo-4-chloro-3-idolyl-β-dgalactopyranoside (X-gal) and incubated at 37 °C for 24 h. Strain was characterized
and identified using biochemical and morphological studies and verified by MTCC